mbed TLS v2.11.0
Functions
hkdf.h File Reference

This file contains the HKDF interface. More...

#include "md.h"
Include dependency graph for hkdf.h:

Go to the source code of this file.

Macros

HKDF Error codes
#define MBEDTLS_ERR_HKDF_BAD_INPUT_DATA   -0x5F80
 

Functions

int mbedtls_hkdf (const mbedtls_md_info_t *md, const unsigned char *salt, size_t salt_len, const unsigned char *ikm, size_t ikm_len, const unsigned char *info, size_t info_len, unsigned char *okm, size_t okm_len)
 This is the HMAC-based Extract-and-Expand Key Derivation Function (HKDF). More...
 
int mbedtls_hkdf_extract (const mbedtls_md_info_t *md, const unsigned char *salt, size_t salt_len, const unsigned char *ikm, size_t ikm_len, unsigned char *prk)
 Take the input keying material ikm and extract from it a fixed-length pseudorandom key prk. More...
 
int mbedtls_hkdf_expand (const mbedtls_md_info_t *md, const unsigned char *prk, size_t prk_len, const unsigned char *info, size_t info_len, unsigned char *okm, size_t okm_len)
 Expand the supplied prk into several additional pseudorandom keys, which is the output of the HKDF. More...
 

Detailed Description

This file contains the HKDF interface.

The HMAC-based Extract-and-Expand Key Derivation Function (HKDF) is specified by RFC 5869.

Definition in file hkdf.h.

Macro Definition Documentation

◆ MBEDTLS_ERR_HKDF_BAD_INPUT_DATA

#define MBEDTLS_ERR_HKDF_BAD_INPUT_DATA   -0x5F80

Bad input parameters to function.

Definition at line 36 of file hkdf.h.

Function Documentation

◆ mbedtls_hkdf()

int mbedtls_hkdf ( const mbedtls_md_info_t md,
const unsigned char *  salt,
size_t  salt_len,
const unsigned char *  ikm,
size_t  ikm_len,
const unsigned char *  info,
size_t  info_len,
unsigned char *  okm,
size_t  okm_len 
)

This is the HMAC-based Extract-and-Expand Key Derivation Function (HKDF).

Parameters
mdA hash function; md.size denotes the length of the hash function output in bytes.
saltAn optional salt value (a non-secret random value); if the salt is not provided, a string of all zeros of md.size length is used as the salt.
salt_lenThe length in bytes of the optional salt.
ikmThe input keying material.
ikm_lenThe length in bytes of ikm.
infoAn optional context and application specific information string. This can be a zero-length string.
info_lenThe length of info in bytes.
okmThe output keying material of okm_len bytes.
okm_lenThe length of the output keying material in bytes. This must be less than or equal to 255 * md.size bytes.
Returns
0 on success.
MBEDTLS_ERR_HKDF_BAD_INPUT_DATA when the parameters are invalid.
An MBEDTLS_ERR_MD_* error for errors returned from the underlying MD layer.

◆ mbedtls_hkdf_expand()

int mbedtls_hkdf_expand ( const mbedtls_md_info_t md,
const unsigned char *  prk,
size_t  prk_len,
const unsigned char *  info,
size_t  info_len,
unsigned char *  okm,
size_t  okm_len 
)

Expand the supplied prk into several additional pseudorandom keys, which is the output of the HKDF.

Parameters
mdA hash function; md.size denotes the length of the hash function output in bytes.
prkA pseudorandom key of at least md.size bytes. prk is usually, the output from the HKDF extract step.
prk_lenThe length in bytes of prk.
infoAn optional context and application specific information string. This can be a zero-length string.
info_lenThe length of info in bytes.
okmThe output keying material of okm_len bytes.
okm_lenThe length of the output keying material in bytes. This must be less than or equal to 255 * md.size bytes.
Returns
0 on success.
MBEDTLS_ERR_HKDF_BAD_INPUT_DATA when the parameters are invalid.
An MBEDTLS_ERR_MD_* error for errors returned from the underlying MD layer.

◆ mbedtls_hkdf_extract()

int mbedtls_hkdf_extract ( const mbedtls_md_info_t md,
const unsigned char *  salt,
size_t  salt_len,
const unsigned char *  ikm,
size_t  ikm_len,
unsigned char *  prk 
)

Take the input keying material ikm and extract from it a fixed-length pseudorandom key prk.

Parameters
mdA hash function; md.size denotes the length of the hash function output in bytes.
saltAn optional salt value (a non-secret random value); if the salt is not provided, a string of all zeros of md.size length is used as the salt.
salt_lenThe length in bytes of the optional salt.
ikmThe input keying material.
ikm_lenThe length in bytes of ikm.
[out]prkA pseudorandom key of at least md.size bytes.
Returns
0 on success.
MBEDTLS_ERR_HKDF_BAD_INPUT_DATA when the parameters are invalid.
An MBEDTLS_ERR_MD_* error for errors returned from the underlying MD layer.